1. Field of the Invention
The present invention relates to a method of making a huge underground space whose size is comparable to a town or city space.
2. Description of Related Art
Japanese Patent 3-39,600(A) shows a method of making such a huge underground space, which is illustrated in FIG. 19. FIG. 20 shows the manner in which a huge underground space is made. First, two longitudinal holes (not shown) are made at an elongated interval in the earth. A shield driving machine M is driven in one direction from one longitudinal hole to the other longitudinal hole to make one lateral sector shell-unit S having passage P therein extending between the opposite longitudinal holes. Then, the shield driving machine M is driven in the other direction from the other longitudinal hole to the one longitudinal hole to make another lateral sector shell-unit S running adjoiningly and parallel to the first lateral shell-unit. This lateral shell-unit making process is repeated until a plurality of lateral shell-units are continuously arranged on the circumference of a huge circle, thus forming the outer shell of the huge underground space. Then, the lateral shell-unit making process is repeated until a plurality of lateral shell-units are continuously arranged on a horizontal chord. By using power shovels the soil is removed from the major and minor segments of the huge circle which are delimited by the outer shell.
Accurate arrangement of a plurality of lateral shell-units on the circumference of huge circle is very difficult. Minor positioning errors are likely to be accumulated to prevent both ends of the open loop from meeting together at the final stage. Workers in adjacent lateral passages make reinforced concrete structures to connect adjacent lateral shell-units. This requires much laborious work and cost.